Blender game engine camera
Your question covers a lot of ground.
For starters, I recommend you set up 4 separate cameras. This is easier than having your camera move to the different desired positions.

switching between cameras requires a spot of code (at least the way I've done it.)
however if you wish to display your separate views simultaneously, a tutorial to check into is https://www.youtube.com/watch?v=-TtTBGSOii4.

as far as seeing through your own head: make sure your render settings are set to 'Blender Game' and turn to the material properties of your object. Click the check mark next to Backface culling. This should allow you to view the world though your own head.